How to make holes in several plains at once
Final:



Simplest way with quad topology would be to cut holes in Subdivided Plane and add Subdivision Surface modifier.

Steps:




Create a Plane.
Go to Edit Mode and Subdivide it twice. First time with 10 cuts, second one with 1. You can go further if you need different hole placement.
Select faces where you want your holes and delete them.
Remove unnecessary faces to trim page as you want.
Select outer edge of the mesh and add to it Mean Crease > 1. This will ensure that corners stay sharp after Subdivision Surface modifier will be added.
Add Subdivision Surface modifier. I've set it to 2.


Final touches:



If you want smaller holes you can select Edge Loop around them in Edge Select mode, switch to Pivot Center > Individual Origins, then Extrude and Scale them down.